Embodiments of the present invention generally relate to methods for the recovery of fractionated water, and specifically relate to methods to recover salt and condensed water from fractionated water under low temperature and pressure conditions.
Hydraulic fracturing is a process applied to drilled oil and gas well holes to improve the ability of fluids (such as oil and gas) to flow from the petroleum bearing formation to the drill hole. It involves injecting high pressure fracturing fluid into the rock formation with various additives, thereby causing the formation to fracture circumferentially away from the hole. During the fracturing process, the injected fracturing fluid is recovered, while the oil and gas flows from the rock formation into the drill hole and up to the well surface. The fracturing process is often necessary for economical well production.
The fractionation of water results from the hydraulic fracturing process, specifically, the chemical additions that are typically used as part of the fracturing process. In the fracturing process, sand is forced under pressure into the cracks that are pressure induced into the oil or gas underground formation. The sand is carried deep into the cracks of the formation by a viscous gel. The gel is “broken” to allow the release of sand at the sand's point of furthest ingress into the formation crack. Typically, the breaking process is initiated by an enzyme breaker. Upon breaking, the fractionated water is removed from the well, and may be treated with one or more treatment methods.
Many oil and natural gas operations generate significant quantities of fractionated water, in addition to their desired hydrocarbon products. Typically, fractionated water is contaminated with significant concentrations of chemicals that require treatment before the water may be reused or discharged to the environment. Fractionated water may contain natural contaminants that are mixed with the water as a result of the fracturing process, such as hydrocarbons and inorganic salts. It may also contain synthetic contaminants, such as spent fracturing fluids including polymers and inorganic cross linking agents, polymer breaking agents, friction reduction chemicals, and lubricants. These synthetic contaminants, which are utilized in the drilling process, remain in the fractionated water upon extraction to the surface
Some methods used to recover and process fractionated water utilize a series of evaporators, each one having a higher temperature than the preceding one. Such methods consume tremendous amounts of energy and require specialized boiler plant operators.
Accordingly, there remains a need for a recovery unit for fractionated water that is energy efficient, and cost effective.